Investment Securities - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Marketable Securities [Line Items]
Security Owned and Pledged as Collateral Carrying Value	$ 324,400,000	$ 158,800,000
OTTI		0	$ 0
Realized Investment Gains (Losses)	1.5	24,000	173,000
Realized Investment Gains Losses, Net of Tax	1.2	19,000	$ 136,000
Equity securities	1,090,000
Gain (loss) on equity securities	90,000	$ 0
Preferred Stock [Member]
Marketable Securities [Line Items]
Equity securities	$ 1,100,000